Quantification of ultrasound images often requires the identification of a border of an object of interest in the ultrasound image. For example, the left ventricle endocardial border often needs to be identified for quantification of left ventricle ejection fraction and left ventricle volume. Typically, a user manipulates on-screen cursors to manually trace the border on an ultrasound image.
New ultrasound imaging modalities, such as tissue harmonic imaging, contrast agent imaging, and intracardiac imaging, can provide better delineation between the different objects in the imaging region as compared to traditional B-mode gray-level and CD-mode color ultrasound images. For example, harmonic color-Doppler imaging with contrast agent enhancement has been shown to provide good blood pool-border delineation. As described in "Quantitative Left Ventricular Volume and Ejection Fraction by 3D Contrast Harmonic Color Doppler Left Ventriculography Compared to Equilibrium Gated Radionuclide Ventriculography," Schwartz, Bezante, Chen, and Villa, images acquired from the apical views of the left ventricle using this imaging modality produce vivid endocaridal delineation that can be used to accurately measure left ventricle volumes and left ventricle ejection fraction.
Even with the use of new ultrasound imaging modalities to improve the delineation between different objects in the imaging region, time-consuming manual border tracing is still widely used due to the lack of robust automatic border detection techniques. One of the difficulties encountered in existing techniques is that the object of interest in the imaging region is not sufficiently isolated from neighboring anatomy with similar properties. For example, the border of part of the right ventricle is sometimes identified as part of the border of the left ventricle. Additionally, the accuracy of these automatically-generated borders is often not sufficient for quantification applications that depend on a precise boundary.
Accordingly, there is a need for a diagnostic medical ultrasound system and method for object of interest extraction that will overcome the problems described above.